A manufacturing process for an ophthalmic lens is already established in DE 38 17 850 A1. The exact shape of the ophthalmic lens as well as the aperture point and the mounting point relative to a coordinate system for the ophthalmic lens is thus first measured. The cross-section of the ophthalmic lens is then calculated in n-sections with reference to the coordinate system, whereby this calculation is repeated till an optimal ophthalmic lens with a minimal central thickness is calculated in the case of a minimal rim thickness predetermined by the spectacle frame. After aligning and blocking the blank, the ophthalmic lens is then milled, ground and polished corresponding to the previously determined values.
A manufacturing process for ophthalmic lenses is, furthermore, established in DE 103 18 597 35 A1. The semi-finished products in this process are used with optically-effective lens rear sides at which they are blocked on block pieces. The parts are subsequently inserted in the mounting devices by computer numerically controlled machining tools where mechanical machining of the convex lens front side takes place. The work piece is blocked in the case of all mechanical machining processes for the manufacture of the optically-effective convex lens front side. Its round shape, which corresponds to the diameter of the semi-finished product, is thereby retained. Thickness-optimization takes place during mechanical machining and a work piece contour is produced which is formed in such a manner that it gradually inclines downwards, beginning from the center of the work piece and moving outwards, whereby the convex lens front side is formed. This ends in a virtual contour. The curvature direction of the work piece contour reverses from the virtual contour, due to which the work piece contour increases again in the case of further outward progression, whereby a concave, circular supporting rim is formed.
With regard to the methods in accordance with the invention, embodiments in DE 103 18 597 A1, paragraphs 2 to 25 will be referred to explicitly further to prior art and to the background.
The theory in DE 103 18 597 A1 deals, on the one hand, with the problem of thickness, particularly the thickness of the rim of the glasses in accordance with DE 38 17 851 A1. DE 103 18 597 A1 contains a supplemental description for provision of a supporting rim that is attached to a virtual contour of the glass i.e., a virtual rim line of the glass, in order to increase stability in the region of this virtual rim and to increase the quality of surface machining, especially in this virtual rim zone. For this purpose, the theory in DE 103 18 597 A1 dispenses with rim machining of the ophthalmic lens. The diameter remains unchanged. During the entire manufacturing process, the work piece ought to retain the circular shape and the diameter of the semi-finished product so that standardized clamping tools can be used. The curvature of the prescriptive surface is not taken into account when shaping the supporting rim. The prescriptive surface is bordered by the virtual contour and is as large as the required ophthalmic lens.